The Photocatalytic Oxidation Ability of Rb0.9nb1.625mo0.375o5.62 Β-Pyrochlore Compound with Cubic Structure

Previously the non-cubic β-pyrochlore polycrystalline compounds Rb0.95NbxMo2-xO6.475-0.5x (x = 1.31–1.663) has been obtained in the ternary system Rb2O-Nb2O5 -2MoO3 . However, using special synthesis condition leads to the formation of cubic Fd-3m β-pyrochlore compound Rb0.9Nb1.625Mo0.375O5.62 with small size particles. The Rb0.9Nb1.625Mo0.375O5.62 powder has been investigated by X-ray powder diffraction analysis and scanning electron microscopy with X-ray microanalysis. The crystal structure refinement has been performed using the Rietveld method. The small size particle and surface area of 15 m2/g of the Rb0.9Nb1.625Mo0.375O5.62 powder make it promising for the photocatalytic processes. The electronic structure and band gap of Rb0.9Nb1.625Mo0.375O5.62 have been studied in comparison to similar non-cubic composition Rb0.95Nb1.625Mo0.375O5.66. The photocatalytic properties of the Rb0.9Nb1.625Mo0.375O5.62 powder have been investigated on the example for dyes solution oxidation under UV irradiation. The dependence on the photocatalytic properties of dye type and catalyst mass has been studied. The active radical species and oxidation mechanism have been determined. It has been observed that the main oxidative species for dye oxidation is hydroxyl radicals. The phase and composition stability of catalyst powder have been confirmed.